Transcript Minimally Invasive Spine Surgery

Minimally Invasive Spine Surgery
The last decade has seen an evolution of minimally invasive
spine surgery with new
technological developments.
Minimally invasive spine surgery is thought to decrease
postoperative pain and allow quicker recovery by limiting
soft-tissue retraction and dissection. Advances in microscopy,
tissue retractors, and specialized instruments have enabled
surgeons to perform procedures through small incisions.
As with the open approach, the goals of the minimally
invasive approach are to adequately decompress the involved
neural elements, stabilize the motion segment, and/or realign
the spinal column according to the needs of the individual
patient.
Key Concepts
Minimally invasive posterior lumbar surgery is based on the
following key concepts:
(1)avoid muscle crush injury by self-retaining retractors,
(2)do not disrupt tendon attachment sites of key muscles,
particularly the origin of the multifidus muscle at the
spinous process,
(3)Utilize known anatomic neurovascular and muscle
compartment planes, and
(4)Minimize collateral soft tissue injury by limiting the width
of the surgical corridor.
Kim et al. compared trunk muscle strength between patients treated with open posterior spinal
instrumentation and those managed with percutaneous instrumentation. Patients who had
undergone percutaneous instrumentation had >50% improvement in lumbar extension strength,
whereas those treated with open surgery had no improvement.
Comparison of Multifidus Muscle Atrophy and Trunk Extension Muscle Strength : Percutaneous
Versus Open Pedicle Screw Fixation
Kim, MD,* Sang-Ho Lee, MD, PhD,* Sang Ki Chung, MD SPINE ©2004
Significant decrease in the cross-sectional area of multifidus muscle in the OPF group. In
contrast, the results in the PPF group showed no statistical difference between preoperative &
post operative results.
PPF had positive effects on postoperative trunk muscle performance.
Box plot showing the longitudinal changes of crosssectional area of multifidus muscle and extensor muscle strength in the
percutaneous and open pedicle screw fixation groups. Box plots show the median value (horizontal line in box), and
interquartile range (25%–75%) is represented by the box
Muscle biopsy specimens from patients undergoing revision spine surgery have
revealed selective type-II fiber atrophy, widespread fiber-type grouping (a sign of
reinnervation), and a ‘‘motheaten’’ appearance of muscle fibers. the most important
factor responsible for muscle injury is the use of forceful self retaining retractors.
Kawaguchi et al. proposed that injury is induced by a crush mechanism similar to that
caused by a pneumatic tourniquet during surgery on the extremities. The severity of
the muscle injury is affected by the degree of the intramuscular pressure and the
length of the retraction time. Patients treated with a traditional open posterior
transforaminal lumbar interbody fusion technique showed marked intramuscular
edema on postoperative MRI six months after
the surgery.
Tsutsumimoto et al. used MRI to compare two groups of patients: those who had
had a traditional midline approach and those who had had a mini-open Wiltse
approach. The degree of multifidus atrophy and the increase in T2-signal intensity in
the multifidus muscle after the miniopen posterior lumbar interbody fusion were
significantly lower than those following open posterior lumbar interbody fusion
Damage to the neuromuscular junction following prolonged retraction can also lead
to muscle denervation. Muscle biopsies in patients with failed back surgery
syndrome showed signs of advanced chronic denervation
.
Kim et al. compared levels of circulating markers of tissue injury in
patients who had undergone open spinal fusion with those in patients
treated with minimally invasive spine surgery.
The levels of creatinine kinase, aldolase, pro-inflammatory cytokines (IL6 [interleukin-6] and IL-8), and antiinflammatory cytokines (IL-10 and IL1 receptor antagonist) in the patients
treated with the open surgery were altered several-fold compared with
those in the patients treated with the minimally invasive surgery. Most
markers returned to baseline levels by three days after the minimally
invasive surgery, whereas they required seven days to return to
baselines levels after the open surgery
Ren et al. demonstrated that the glycerol concentrations in the
paraspinal muscles of patients who had undergone posterolateral
lumbar fusion with instrumentation were higher than the
concentrations in the deltoid muscles of the same patients.
Another goal of minimally invasive spine surgery is to limit the amount of osseous
resection to minimize postoperative spinal instability. The disruption of facet joint
integrity combined with loss of the midline interspinous ligament-tendon complex
associated with traditional laminectomy can contribute to flexion instability.
A finite element analysis demonstrated that minimizing bone and ligament
removal resulted in greater preservation of normal motion of the lumbar spine
after surgery.
Efforts to limit such potentially destabilizing surgery have been pursued via
unilateral laminotomies in which the spinous processes and corresponding
tendinous attachments of the multifidus muscle and the supraspinous and
interspinous ligaments are preserved.
A. Jay Khanna, MD Johns Hopkins Orthopaedics at Good Samaritan Hospital
Laminectomy risks and complications
In approximately 5 to 10% of cases,
postoperative instability of the operated level can be encountered. This
complication can be minimized by avoiding the pars interarticularis. Facet joints
may have to be removed if they are enlarged with arthritis or are pushing on the
spinal nerves, causing instability and may require spinal fusion.
Claudius Thome (JNS) 2005 success rate of laminectomy is only 64%,
failures have been attributed to local tissue trauma and post
operative spinal instability, which has led to dramatic increase in
lumbar fusion surgery.
Carl Lauryssen, MD, Spine 2010, difficulty of accessing a stenotic
neural foramen with linear configured decompression instruments
during traditional or MIS surgery results in resections of part or the
entire facet joint, leading to instability. Destruction of facet joint
transfers axial loads to the anulus and anterior longitudinal ligament,
which may accelerate disc degeneration. This may cause instability
and nonphysiological motion, possibly leading to neural trauma, facet
fracture, disc disruption, or spondylolisthesis. In their retrospective
study, Hopp and Tsou reported that 57 of 344 (16.6%) of patients who
had decompression for stenosis had to undergo additional fusion
surgery because of complications mostly due to instability.
Minimally Invasive Tubular Microdiscectomy
The treatment of herniated discs via minimally invasive tubular microdiscectomy is the most
common minimally invasive spine technique currently used in the United States. This system,
developed by Foley and Smith, consists of a series of concentric dilators and thin walled tubular
retractors of variable length. The tube, typically 18 mm in diameter, circumferentially defines a
surgical corridor. Surgery is typically performed with use of an operating microscope.
Randomized controlled trials comparing traditional open microdiscectomy with minimally
invasive tubular microdiscectomy all showed that tubular microdiscectomy is safe and
efficacious resulted in less intraoperative tissue damage, nerve irritation, blood loss, and
immediate postoperative pain as well as a shorter period of hospitalization and a faster recovery
and return to work
Minimally Invasive Lumbar Decompression
Percutaneous transforaminal endoscopic lumbar discectomy
Ideal for
foraminal and
extra
foraminal
lumbar disc
herniaitons
Spinal stenosis
can be tackled
using laser and
endoscopic
burrs
Minimally Invasive Lumbar Hemilaminectomy
The central canal and the contralateral recess can be decompressed by angling the
tubular retractor dorsally to view the undersurface of the spinous process and the
contralateral lamina The dural tube can be gently pushed down, and the ligamentum
flavum and the contralateral superior articular process are resected to achieve a
bilateral decompression.
Ikuta et al. reported good short-term results in thirty-eight of forty-four patients.The
mean improvement in the Japanese Orthopaedic Association score was 72%.
Postoperative morbidity was relatively low and, compared with a control group treated
with open surgery. Yagi el.al The patients treated with the minimally invasive
decompression had a shorter mean hospital stay, less blood loss, a lower mean
creatine phosphokinase muscle isoenzyme level, a lower visual analog scale score for
back pain at one year postoperatively, and a faster recovery rate. Satisfactory
neurological decompression and symptom relief were achieved in 90% of the patients,
and no patient had spinal instability